One of the great ironies of programming language research is that
language researchers are both the most frequent victims of the Turing
tar pit mentality, as well as its most fervent perpetrators.

The tar pit, as I see it, is the attitude that programming language
research is pointless because no programming language will ever let
you do something that can’t already be done by a Turing machine. The
Turing tar pit is a big problem for language researchers, who need to
convince the rest of computer science that their work is worthwhile.

Within programming languages, the tar pit arises in a hidden form: it
manifests as an unfavorable referee report that roughly translates to,
“this can already be done in my favorite language.” Well,
yes, of course, since by the Church-Turing Thesis, “this can
already be done in my favorite language” is a tautology!
Tautologies, by definition, have no implications, and in particular,
they do not imply that a paper should be rejected.

Recently I’ve started to see a new variant of the Turing tar pit,
something I call the monadic morass. Since monads were
originally popularized in language research as a tool for specifying
the semantics of programming languages, it is no surprise that they
can form the basis for universal computation. So, when someone says
that “this can already be done with monads,” listen
closely and you might hear the sound of good research being sucked
into the Turing tar pit.

How should we judge programming language research while avoiding the
Turing tar pit? That’s a hard question, but another epigram of Perlis
might be a good place to start:

A language that doesn’t affect the way you think about programming, is
not worth knowing.